A biometric is a physical or behavioral characteristics of a person that can be used to determine or authenticate a person's identity. Biometrics such as fingerprint impressions have been used in law enforcement agencies for decades to identify criminals. More recently, other biometrics such as face, iris and signature are starting to be used to identify persons in many types of transactions, e.g., check cashing and ATM use. An automated biometrics identification system analyzes a biometrics signal using pattern recognition techniques and arrives at a decision whether the query biometrics signal is already present in the database. An authentication system tests whether the query biometrics is equal, or similar, to the stored biometrics associated with the claimed identity. A generic automated biometrics system has three stages: (i) signal acquisition; (ii) signal representation and (iii) pattern matching.
Authentication of a person is a fundamental task in many day to day activities. Several well established processes such as possession of driver's license, passwords, ATM cards, PINs and combinations thereof are used depending on the level of security needed by the application. Transaction oriented systems such as bank ATMs, point-of-sale terminals in retail stores require authentication tools for every transaction session. In a typical transaction, the client computer (ATM machine, cash register) transmits the account details of the customer as read from his card and the transaction details as entered by the clerk (or customer) to an authorization server. The authorization server checks the validity of the account, the account balance and credit limit, and then approves or rejects the transaction. Approved credit card transactions result in payment from the credit card banking agencies to the store; approved ATM withdrawal transactions result in delivering of cash by the ATM. For transactions such as the self-serve purchase of gasoline, simply the possession of a credit card is often enough. There is no attempt to determine that the card is used by the rightful owner. Except for the use of PINs (in ATMs and for debit cards) or a signature on the credit card authorization slip in a store, there is very little done to authenticate the user. Biometrics can play a significant role in such scenarios.